Manufacture of die castings



Jan.1,1929. '1,697,741

C. VAUGHAN l MANUFACTURE OF `DIE CASTINGS Filed Oct. 22, 1927 FIGA.

Patented Jan. A1, 1929.

l l1,69"7,741 UNITED STATES PATENT oFEicE.

CONRAD VAUGHA-N, F HANDWOR'IH, BIRMINGHAM, ENGLAND.

MANUFACTURE O DIE CASTINGS.

Application filed October 22, 1927, Serial' No. 228,040, and in Great Britain 4September 10, 1927.

This invention relates to the manufacture of die-castings and lalthough applicable to die castings generally is particularly intended '-for application to pressure die castings.

In connection with die lcastings generally and particularly with pressure die castings it is well known that such castings are particularly subject to blow holes in the interior, especially in the thicker. portions of such castings.

It is believed vthat these blow holes are formed by the air which is in the die before .the metal ent-ers such air being unable to leave the die and consequently forming pockets inthe interior of the casting.

The object of the present 'invention is to provide certain improvements whereby this defect can be overcome.

According to the present invention the die is formed with one or more expanding charnbers, such chambers being provided particularly where the thicker parts of the metal are to be formed, the arrangement 'being such that prior to the metal entering the die, such chambers are collapsed or partially collapsed so that the amount of air at such positions is milch reduced and the chamber or chambers expanding as the metal runs into the die.

The expanding die or the expanding portion of the die may be formed by providing movable portions of piston'like or plunger like form in the die at those positions where the metal in the finished casting is to be thickest, the piston like or plunger like portions moving outwardly as the metal enters.

the portions of the die where they are situated.

The piston like'or plunger like portions may be moved outwardly by the pressure of the incoming'moltenmetal and suoli out-AV ward movement may take place against a suitable resistance which may be provided by a dash pot or a spring or similar device.

Referring to the drawings Figure l-is a view in section illustrating a simple form of my invention. A

Figure 2 is a view in section showing another application of Iny invention. Figure 3 is a sectional view showing a third method of application of the invention. Referring to Figure 1, the die 1 is pro videdwith a piston like member 2 forming a movable side to the die.

The'usual opening is provided at 3 for the nozzle through which the incoming metal is, forced.

The piston like portion 2 is provided with a rod 22 having a collar 4 against which acts a strong spring 5 supported by a suitable abutment. In such a die assuming that the piston 2 1s not provided, when the metal is forced through the nozzle the `air in the die is unable to escape and the incoming metal tends to flow round the walls of the cavity within the die so that the air is eventually enclosed in the linished casting, which is thus hollow or very porous.

In the apparatus illustrated, however, the

amount of air in the die before the entrancev 'of the molten metal is reduced to a negligible the space 7.

As the metal enters the pressure thereof quantity, such air being contained only in drives back the piston 2 until its rear wall 8 meets the part 9 of the die, and it isfound that a non-porous -casting which is free from blow holes can thus be produced.

If required a' suitable outlet may be provided for the air which. is ypresent behind the piston before the metal is introduced.

In the arrangement shown in Figure 2 the casting to beproduced is of substantially constant thickness'except for a portion tobe produced at 10, and this portion is provided with a plungervlike member 11 so that theair in the portion 10 is much reduced at the start.

Upon the metal entering through the nozzle which is fixed in the opening 12, it Hows into the cavity of the die and drives back the plunger 11 which is fitted with a dash pot appliance 13 until the whole of the cavitylO becomes filled with metal.

If required, the dash pot device may be provided with a valve of any suitable or Well known construction so that the resistance of fered thereby can be adjusted.

In the arrangement shown in Figure 3 the die 14 is shaped for producing a casting consisting of abar portion 15 having a number of lumps or projecting pieces 16 thereon.

Normally the lumps or projecting pieces 16 would be found to be porous or to contain serious blow holes and according to the present invention eac'h of the portions 16 is may be all connected together by a transverse bar 19 which has a rod 20 to which a spring Aor dash pot resistance is applied.

v. 17 are driven back by the pressure thereof.

What I claim then is 1. Apparatus for the manufacture of die castings comprising a mold, and a fluid actuated plunger Withinsaid mold adapted `to recede therein under the action of the Huid entering the mold.

2. Apparatus for the manufacture of die castings comprising a mold, a plunger disposed Within that part of the mold Where the finished casting is to he thickest, and means for controlling the movement of said plunger.

3. Apparatus for the manufacture of die castings comprising a mold having a recess in its inner Wall, a fluid actuated plunger adapted to work in said recess and to recede therein under the action of the fluid entering the mold, and means for controlling the movement of said plunger.

4. Apparatus for the manufacture of die castings comprising a mold having a recess in its inner Wall at that part Where the finished casting is to be thickest, a fluid actuated plunger adapted to Work in said recess and to recede, therein under the action of the fluid entering the mold, and hydraulic dash pot means adapted to control the movement of the said plunger.

5. Apparatus for the manufacture of die castings comprising a mold, a plunger projecting into said mold at one side of the same to displace certain of the air content thereof,v

and means for admitting molten metal to the 4interior of the mold, said plunger being adapted to recede outwardly of the mold under the action thereon of the incoming metal. In Witness whereof I alix my signature.

CONRAD VAUGHAN. 

